This invention relates to an electrical connector having a shell for electromagnetic shield and, in particular, to such an electrical connector for use on a printed circuit board having a ground pattern to which the shell is connected.
A conventional electrical connector with a shell generally comprises an insulator and the shell attached to the insulator. The insulator has a base portion, a fitting or mating portion formed on a main surface of the base portion and fitting to, or mating with, a mating connector, and a pair of blocks formed at longitudinal opposite ends of the base portion.
Each of the blocks has an installation surface perpendicular to the main surface. The mating portion is equipped with a plurality of electroconductive contacts.
The shell is made of a metallic plate and fitted onto the mating portion to electromagnetically shield the contacts. The shell comprises a tubular portion for covering or surrounding the mating portion, and a flange radially extending from a peripheral edge of the tubular portion and received by the main surface. The longitudinal opposite ends of the flange extend as flange end portions onto, and received by, receiving surfaces of the blocks. The base portion has a pair of base surfaces at upper and lower sides thereof. Each of the base surfaces is provided with a plurality of projections. A plurality of coupling portions are formed to extend from the flange portion of the shell along the base surfaces for one-to-one engagement with the projections. Each of the coupling portions is formed into a lug having a slot into which the corresponding projection is fitted.
In order to attach the shell to the insulator, the shell is fitted onto the mating portion. In the fitting operation, the coupling portions are firstly brought into contact with the projections and then urged by the projections to be elastically deformed so that the tubular portion is subjected to a force to partially expand the peripheral edge. When the coupling portions are further forced to pass over the projections, the projections are snapped into the slots to make engagement with the coupling portions.
In the meanwhile, the above-mentioned electrical connector with a shell is for use in an electronic apparatus and is required small in size and thin in shape. This is because of a demand for effective utilization of a space in a small-sized apparatus.
However, if the electrical connector with a shell is formed small and thin, the shell is inevitably formed of a metal plate having a reduced thickness. In this situation, the shell is readily deformed when subjected to a force to expand an opening edge of the tubular portion of the shell, for example, in the fitting operation of the shell to the insulator.
The conventional electrical connector with a shell is often used onto a printed circuit board in the prior art.
There are known two types of mounting arrangement for mounting the electrical connector with a shell onto a surface of the printed circuit board.
According to one type, a pair of electroconductive hook lugs are respectively attached to the blocks formed on longitudinal opposite ends of the base portion. Each of the hook lugs is provided with a hook pin. Each hook pin has leg portions adapted to pass through a through hole formed on the printed circuit board. An engagement piece is formed on an end of each leg portion and is protruded from a rear surface of the printed circuit board. The engagement pieces of each hook pin are fixed onto the rear surface of the printed circuit board by means of soldering.
Terminal portions of the contacts pass through the printed circuit board to be connected to a wiring pattern formed on the rear surface of the printed circuit board. The shell is electrical connected to a ground pattern on the rear surface of the printed circuit board through the hook lugs, the hook pins, and screws for mounting the connector onto a panel of an apparatus.
In this type, since the hook pins are bonded by soldering onto the rear surface of the printed circuit board while the electrical connector being mounted on the opposite surface of the printed circuit board, infrared-radiation reflowing can not be used for connecting the hook pins to the ground pattern by soldering.
In another known structure for mounting the conventional electrical connector with a shell, the insulator is positioned on the printed circuit board by means of positioning pins formed at a bottom of the insulator. Each block is provided with a holding member at a side thereof. The holding member is bonded by soldering on the printed circuit board, so that the insulator is fixed to the printed circuit board.
Terminal portions of contacts are for connection with a wiring pattern formed on the top surface of the printed circuit board and extend on, and are bonded to, the wiring pattern by soldering.
In the mounting structure, it is difficult to assure tight contact between the insulator and the printed circuit board. The extending ends of the terminal portions often float up before soldering. This results in non-uniform contact between the top ends of the terminals portions of the contacts and the wiring pattern on the printed circuit board.
As described, it is impossible in the conventional electrical connector with a shell to suppress floating of the top ends of the terminal portions before soldering. As a result, it is difficult to assure reliable connection between the contacts and the wiring pattern on the printed circuit board.